If you look at the past 12 to 18 months it becomes obvious why ...
Roughly 18 months ago (at TGS 2005) we were first introduced to the Wiimote. There was a massive polarized reaction as half the people who saw the video proclaimed it the greatest thing ever, and everyone else believed it was Nintendo's doom. The general consensus at this point in time was that Sony was not going to repeat the mistakes of Microsoft produce two SKUs and price their system at the "outrageous" $400. The expectation at this point was that the Revolution would be a Niche product and the PS3 would dominate.
Roughly 12 to 14 months ago Nintendo released the DS Lite, Nintendogs and Brain Age and changed the Japaneese market forever. The DS started selling faster than (practically) every system and moved more games than anyone could imagine; Nintendo expaneded the market beyond what anyone had ever expected.
12 months ago, at E3 2006, the PS3 was announced to cost $500/$600 and everyone was shocked. At the same time the Wii had 6 hour line-ups every day for the opportunity to try the Wii.
6 Months ago both systems were released and, while the Wii sells remarkably quickly the PS3 has sold far below expectations.
It is not surprising after how much has changed to see developers targeting the Wii as compared to the PS3.
